Development and regeneration of the nervous system involve a complex set of interactions between cell types (neurons, glia, Schwann cells), and between cells and extracellular matrix materials such as glycoproteins and glycosaminoglycans. Only a few of the molecules on the surfaces of nervous system cell that are involved in these interactions have been identified. The importance of extracellular matrix molecules in nerve development is just now being recognized. One extracellular matrix molecule that be important is laminin, a basement membrane glycoprotein. Laminin is found in peripheral nerves, and is also transiently seen in the brain during development and following injury. Laminin promotes rapid neurite elongation from CNS and PNS neurons. It is synthesized by Schwann cells and may be important in their differentiation. The specific aims of this grant proposal are to examine more closely the interactions between neurons, glia, and Schwann cells with fragments of laminin in order to identify regions of laminin important for cell- laminin interactions; to isolate molecules from the surfaces of neural and glial cells that are involved in the cell-laminin interactions; to make monoclonal and polyclonal antibodies to these cell surface laminin-binding molecules; and, to test the effects of the antibodies against laminin-binding molecules on neuron-laminin and neuron-glial cell interactions, as well as neurite elongation on laminin. Laminin fragments will be used in cell adhesion and neurite outgrowth studies to identify important subregions of the molecule. Laminin binding molecules will be isolated from neural and glial cells by laminin affinity chromatography, and will be used to produce polyclonal and monoclonal antibodies. The antibodies will be tested for the ability to block neuron-laminin and glial-laminin interactions in cell adhesion and radioreceptor assays. The antibodies will also be tested for the ability to interfere with neurite elongation on laminin, and neuron-glial cell interactions. One long term goal of these studies is to identify differences between CNS and PNS that prevent but not develop methods to manipulate brain and spinal cord tissue to allow repair and regeneration following injury.